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近年来超快激光技术的发展为太赫兹波脉冲的产生提供了稳定、可靠的激光发源, 使太赫兹波研究获得长足发展[1]. 超表面作为一种新型二维人工超材料, 可以有效控制电磁波的透射、反射与极化等参量, 因此备受各国研究人员关注. 另外, 利用 VO2[2,3]、石墨烯[4,5]和锑化铟[6,7]等构建复合超表面结构可以实现对微波、太赫兹波和光波的动态调控[8-10]. 最近, 可调太赫兹吸收器作为太赫兹波调控器件之一, 引起研究人员广泛关注[11,12]. 2018年, Hu等[13]利用石墨烯构建不对称分裂环图案层获得多重共振, 实现太赫兹波双宽带吸收器. Yang等[14]利用8个尺寸渐变的单元组成光栅结构实现对TM和TE两种偏振波在不同频率的高效吸收. 2019年, Yan等[15]采用不同尺寸石墨烯方环设计了可调谐的双频点太赫兹吸收超表面. 2020年, Divdel等[16]利用希尔伯特分形结构设计出拥有多个吸收波段的太赫兹超表面吸收器, 吸收率大于90%. 上述报道的超表面主要针对线极化太赫兹波入射实现吸收, 没有对圆极化入射到该类型超表面结构产生何种效果进行研究分析. 最近, Zhao等[17]提出基于阿基米德螺旋结构设计超表面实现对左旋圆极化(left-handed circularly polarized, LCP)波吸收的同时也对右旋圆极化(right-handed circularly polarized, RCP)波产生完全反射. 2022年, Liang等[18]利用VO2和石墨烯构建复合超表面结构通过改变VO2相变状态, 实现对圆极化波的非选择性完美吸收与选择性完美吸收功能可切换. VO2是一种典型的温控相变材料, 其电导率在相变过程中会发生巨大突变. 当低于临界温度(68 ℃)时, VO2具有高电阻率和良好的绝缘性能, 而高于临界温度时, 电阻由高阻态变为低阻态且表现出金属特性. 因此, 将VO2嵌入超表面中组成复合超表面结构, 实现工作频点可切换, 非常有必要研究VO2复合型超表面的太赫兹特性.
本文提出一种VO2复合型超表面实现对线极化和圆极化太赫兹波高效吸收. 当VO2绝缘态(σ = 0 S/m)时, 在频率1.3 THz处, 所设计超表面对LCP波吸收率达到95%, 对RCP波产生完全反射, 圆二色性(CD)为0.85. 当VO2金属态(σ = 2×105 S/m)时, 在频率1.95 THz处, 所设计超表面对TE线极化入射波的吸收率达到98.5%. 研究发现该结构对线极化和圆极化入射波均能实现广角吸收, 有望为太赫兹的新型探测器和传感器设计提供多样性的选择.
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本文提出的太赫兹吸收器结构, 如图1所示, 其工作频率可切换, 对线极化和圆极化入射的太赫兹波均产生完美吸收. 该复合超表面由嵌入VO2的金属图案层, 石英基体和金属底板组成. 利用CST Microwave Studio软件优化后复合超表面结构尺寸: 周期为60 μm, w1 = 4 μm, w2 = 1 μm, 方环长度为44 μm, 圆环外半径为15 μm, θ = 70°, 石英基体厚度为18.5 μm. VO2的相对介电常数利用Drude模型可表示为[19]
图 1 所设计的工作频率可切换, 对线极化和圆极化入射波均产生完美吸收的太赫兹吸收器结构示意图 (a) 三维结构图; (b) 单元俯视图
Figure 1. Schematic diagram of the designed terahertz absorber with switchable operating frequency and perfect absorption for both linearly polarized and circularly polarized waves incidence: (a) 3D structure diagram; (b) top view of the unit.
$ \varepsilon (\omega ) = {\varepsilon _\infty } - {{\omega _{\text{p}}^{\text{2}}(\sigma )}}/({{{\omega ^2} + {\text{i}}\gamma \omega }}) , $ 式中, ε∞ = 12, 碰撞频率γ = 5.75×1013 rad/s, ωp(σ)为等离子体频率.
当圆极化太赫兹波垂直入射到超表面结构时, 连接入射场
$ \left( {E_{\text{R}}^{\text{i}}, {\text{ }}E_{\text{L}}^{\text{i}}} \right) $ 和反射场$ \left( {E_{\text{R}}^{\text{r}}, {\text{ }}E_{\text{L}}^{\text{r}}} \right) $ 的Jones矩阵可表示为[20]$ \left( \begin{gathered} E_{\text{R}}^{\text{r}} \\ E_{\text{L}}^{\text{r}} \\ \end{gathered} \right) = \left( {\begin{array}{*{20}{c}} \begin{gathered} {r_{ + + }} \\ {r_{ - + }} \\ \end{gathered} &\begin{gathered} {r_{ + - }} \\ {r_{ - - }} \\ \end{gathered} \end{array}} \right)\left( \begin{gathered} E_{\text{R}}^{\text{i}} \\ E_{\text{L}}^{\text{i}} \\ \end{gathered} \right) = {{\boldsymbol{R}}_{{\text{circ}}}}\left( \begin{gathered} E_{\text{R}}^{\text{i}} \\ E_{\text{L}}^{\text{i}} \\ \end{gathered} \right) \text{, } $ 式中, r++和r–+分别为右圆极化波入射下的共极化和交叉极化反射系数, r––和r+–为左圆极化波入射下的共极化和交叉极化反射系数. Rcirc为圆极化的反射矩阵, 该矩阵由线极化反射系数表示为
$ {{\boldsymbol{R}}_{{\text{circ}}}}{\text{ = }}\left( {\begin{array}{*{20}{c}} \begin{gathered} {r_{ + + }} \\ {r_{ - + }} \\ \end{gathered} &\begin{gathered} {r_{ + - }} \\ {r_{ - - }} \\ \end{gathered} \end{array}} \right) = \frac{1}{2}\left( {\begin{array}{*{20}{c}} \begin{gathered} {r_{xx}} + {r_{yy}} + {\text{i}}({r_{xy}} - {r_{yx}}) \\ {r_{xx}} - {r_{yy}} + {\text{i}}({r_{xy}} + {r_{yx}}) \\ \end{gathered} &\begin{gathered} {r_{xx}} - {r_{yy}} - {\text{i}}({r_{xy}} + {r_{yx}}) \\ {r_{xx}} + {r_{yy}} - {\text{i}}({r_{xy}} - {r_{yx}}) \\ \end{gathered} \end{array}} \right) \text{, } $ 式中, rxx(ryy)和rxy(ryx)分别为线性波入射下的共极化和交叉极化反射系数. 若所设计结构对LCP入射波完全吸收并对RCP入射波完全反射, 此时反射系数满足条件为r–– = r–– = r+– = 0, r–+ = 1,则线极化反射系数可表示为
$ \left( {\begin{array}{*{20}{c}} \begin{gathered} {r_{xx}} \\ {r_{yx}} \\ \end{gathered} &\begin{gathered} {r_{xy}} \\ {r_{yy}} \\ \end{gathered} \end{array}} \right) = \frac{{{{\text{e}}^{{\text{i}}\alpha }}}}{2}\left( {\begin{array}{*{20}{c}} \begin{gathered} 1 \\ - {\text{i}} \\ \end{gathered} &\begin{gathered} - {\text{i}} \\ 1 \\ \end{gathered} \end{array}} \right) \text{, } $ 式中, α为任意相. 若所设计的复合超表面结构要实现旋向吸波, 则该结构需满足
$ \sin \varphi \left( {\begin{array}{*{20}{c}} \begin{gathered} {r_{xy}} + {r_{yx}} \\ {r_{yy}} - {r_{xx}} \\ \end{gathered} &\begin{gathered} {r_{yy}} - {r_{xx}} \\ - {r_{xy}} - {r_{yx}} \\ \end{gathered} \end{array}} \right) = 0 \text{, } $ 式中, φ代表单元结构旋转一圈后出现与原始结构重合的角度. φ = mπ (m = 0, ±1, ···), 说明只有二重对称结构才能实现对旋向入射波吸波. 除旋转对称结构外, 镜像对称结构若想实现旋向吸收性能, 需满足如下条件:
$ \sin (2\varphi )({r_{xx}} - {r_{yy}}) + 2\cos {r_{xy}} = 0. $ 由(4)式可知, 若(rxx–ryy)/rxy为虚数, 将无法满足(6)式中的镜像对称条件. 因此, 实现旋向选择吸收结构的同时必须打破旋转对称与镜像对称.
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图2表示VO2为绝缘态(σ = 0 S/m)时, LCP波和RCP波入射到复合超表面结构时产生的电磁响应下曲线. 从图2(a)可以看出, LCP波的共极化反射曲线(r––)与RCP波的共极化反射曲线(r++)一致, LCP波的交叉极化反射(r+–)与RCP波的交叉极化反射曲线(r–+)有较大差别. 在频率1.30 THz处, r–+ > 0.9, 而r+– < 0.1, 结果表明在该频点处所设计超表面反射了大部分RCP波, 对LCP波不反射. 为了更加清楚地解释不同圆极化波之间的吸收差, 引入CD进行描述, 定义圆极化吸收率为
图 2 LCP波和RCP波入射下所设计超表面结构的电磁响应曲线 (a)反射系数; (b)吸收率及圆二色性
Figure 2. Electromagnetic response curves of the designed metasurface structures under the incident of LCP and RCP waves: (a) Reflection coefficient; (b) absorption and circular dichroism.
$ {A_{{\text{LCP}}}} = 1 - {({r_{ - - }})^2} - {({r_{ + - }})^2}, $ $ {A_{{\text{RCP}}}} = 1 - {({r_{ + + }})^2} - {({r_{ - + }})^2}, $ 则CD表示为
$ {\text{CD}} = {A_{{\text{LCP}}}} - {A_{{\text{RCP}}}}. $ 从图2(b)可以明显观察到, 在频率1.30 THz处所设计的超表面结构对LCP入射波吸收率达到95%, 但是对RCP入射波吸收率仅为10%, 它的CD值为0.85, 表明几乎所有入射LCP太赫兹波被吸收, 同时大部分入射RCP太赫兹波被反射. 图3是在LCP波和RCP波入射下, 顶层金属结构在1.30 THz处的电场和电流分布图. 由图3(a)和图3(b)可以看出, 当RCP太赫兹波入射时, 在方形缺口环和圆形缺口环的一侧存在单极共振, 但是当LCP太赫兹波入射时, 圆形缺口环产生明显的偶极共振. 同样地, 从图3(c)和图3(d)可以看出, RCP太赫兹波入射时圆环表面电流非常微弱, 而LCP太赫兹波入射时表面电流得到显著增强.
图 3 LCP和RCP太赫兹波入射下的电场分布图与电流分布图 (a) RCP入射下的电场分布; (b) LCP入射下的电场分布; (c) RCP入射下的电流分布; (d) LCP入射下的电流分布
Figure 3. Electric field distribution diagram and current distribution diagram under the LCP and RCP waves incidence: (a) Electric field distribution under RCP incidence; (b) electric field distribution under LCP incidence; (c) current distribution under RCP incidence; (d) current distribution under LCP incidence.
选取超表面结构参数线宽w1, w2和间隙θ研究其对所设计超表面器件CD值的影响情况, 结果如图4所示. 图4(a)表示w1从2 μm增加至4 μm时, 所设计超表面结构的CD只有微小变化, 这是由于LCP入射超表面时方形缺口环的电场能量较弱, 对CD值影响较小. 图4(b)表示随着w2增加, 所设计超表面的CD峰值频率出现蓝移, 且峰值迅速减小, 在w2 = 5 μm处CD值接近于0. 这是由于所设计的超表面结构谐振频率与缺口环等效的电容和电感成反比, 增加线宽会减小表面电流密度和等效电感, 从而使峰值频率发生蓝移. 图4(c)表示所设计超表面的CD峰值对应的频率同样随着θ增加发生明显蓝移, 这是因为圆环缺口可等效成电容, 当缺口角度不断增加时等效电容不断减小, 使得峰值频率向更高频方向移动.
图 4 不同结构参数对所设计超表面的CD影响情况 (a) 线宽w1; (b) 线宽w2; (c) 间隙θ
Figure 4. Influence of different structural parameters on the CD of the designed metasurface: (a) Line width w1; (b) line width w2; (c) angle θ
图5讨论了太赫兹波斜入射角度对所设计超表面结构的圆极化吸收性能影响. 当太赫兹波以入射角70°入射时, 在频率1.30 THz处入射的LCP太赫兹波吸收率大于80%, 如图5(a)所示, 结果表明所设计的超表面具有良好的广角圆极化吸收性能. 图5(b)表示当入射角为70°时, 在频率1.30 THz处, 所设计超表面的CD大于0.7, 表明该超表面在大入射角情况下依旧能够保持着良好的旋向吸收性能.
图 5 入射角对所设计超表面的吸收特性影响 (a) LCP; (b) CD
Figure 5. Incident angle vs. absorption properties of the designed metasurface: (a) LCP; (b) CD.
研究分析在频率0.8—1.6 THz内, 线性太赫兹波(TE极化波与TM极化波)入射到所设计超表面结构产生的吸收特性如图6所示. 从图6(a)可看出, TE波入射下产生的共极化反射曲线(ryy)与TM波入射下产生的共极化反射曲线(rxx)变化趋势一致, TE波入射下产生的交叉极化反射(rxy)与TM波入射下产生的交叉极化反射(ryx)重叠. 在频率1.30 THz处, rxx = 0.35, ryy > 0.53. 如图6(b)所示, 所设计超表面结构在频率1.30 THz处对TE和TM入射波的吸收率分别为43.86%和58.40%.
图 6 TE波和TM波入射下所设计结构的电磁响应曲线 (a) 反射系数; (b) 吸收率
Figure 6. Electromagnetic response curves of the designed structures under the incident of TE and TM waves: (a) Reflection coefficient; (b) absorption.
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当VO2为金属态(σ = 2×105 S/m)时, LCP和RCP太赫兹波入射到所设计的超表面结构时产生的电磁响应曲线见图7. 图7(a)表示在LCP和RCP太赫兹波入射下所设计超表面结构产生的交叉极化反射和共极化反射曲线. 可见, 在频段1.6—2.4 THz内, 两种圆极化波对应的交叉极化和共极化反射曲线完全一致. 图7(b)为LCP与RCP太赫兹波入射到所设计超表面结构获得的电磁波吸收率, 在频率1.95 THz处吸收率大于90%, 圆二色性CD值为0, 此时所设计超表面结构表现为对不同偏振态的太赫兹波没有选择性吸收.
图 7 LCP和RCP太赫兹波入射到所设计超表面结构产生的电磁响应曲线 (a) 反射系数; (b) 吸收率及圆二色性
Figure 7. Electromagnetic response curves of the designed structures under LCP and RCP waves incidence: (a) Reflection coefficient; (b) absorption and circular dichroism.
图8表示TE和TM波垂直入射所设计的超表面结构时产生的太赫兹波反射和吸收谱. 图8(a)中TE与TM极化波入射所设计的超表面结构的交叉反射系数rxy = ryx = 0, 且在1.95 THz处, TM极化波的共极化反射系数rxx > 0.42, TE极化波的共极化系数ryy = 0.12. 图8(b)表示TE和TM波入射到所设计的超表面结构产生的吸收曲线, 在1.95 THz处, 吸收率分别为98.5%和82.0%.
图 8 TE和TM极化太赫兹波入射到复合超表面结构产生的电磁响应曲线 (a) 反射谱; (b) 吸收谱
Figure 8. Electromagnetic response curves of TE and TM polarized terahertz wave is incident on the designed composite metasurface structure: (a) Reflection coefficient; (b) absorption coefficient.
所设计的复合超表面结构对太赫兹波吸收率为A = 1–RT = 1–|S11|2–|S21|2, 式中R和T分别为反射率和透射率, S11与S21是超表面太赫兹波反射参数与透射系数. 由于该复合超表面结构的底层金属板厚度为1 μm, 这远大于太赫兹波的趋肤深度, 因此太赫兹波的透射率为0. 引入阻抗匹配理论[21]分析该复合超表面结构对太赫兹波的吸收特性:
$\begin{split} Z =\;& \sqrt {\frac{{{{(1 + {S_{11}})}^2} - S^2_{21}}}{{{{(1 - {S_{11}})}^2} - S^2_{21}}}} \\ =\;& {{{Z_1}}}/{{{Z_0}}}, \end{split} $ 式中, Z1表示复合超表面结构等效阻抗, Z0 = 120π Ω表示自由空间阻抗. 当等效阻抗与自由空间阻抗匹配时, Z ≈ 1, 此时该结构可以实现完美吸收. 图9表示TE极化波入射到复合超表面时产生的吸收谱与等效阻抗特性. 在频率1.95 THz处, 复合超表面的等效阻抗实部为1.29, 趋近于1, 表明复合超表面在该频率可以实现太赫兹波的完美吸收. 由图10可见, 频率1.95 THz处TE极化波入射到所设计的复合超表面结构时产生的电场能量主要集中在圆环和方环上下侧间隙处, 此频率处的太赫兹波吸收峰是由方环和圆环的偶极共振效应叠加产生.
图 9 TE波入射到复合超表面结构产生的等效阻抗实部与虚部
Figure 9. Real and imaginary parts of the equivalent impedance of the designed composite metasurface structure under the TE wave incidence.
图 10 TE波入射下, 复合超表面结构电场分布
Figure 10. Electric field distribution of the designed composite metasurface structure under TE wave incidence.
图11为线极化波入射下超表面复合结构的不同结构参数对太赫兹吸收性能影响情况. 图11(a)显示当w1从2 μm增加至6 μm时, 复合超表面结构的太赫兹吸收峰出现轻微蓝移, 吸收率仍大于90%. 图11(b)表示随着w2增加, 复合超表面结构的太赫兹吸收峰出现蓝移, 吸收率逐渐降低. 由图11(c)可见, 复合超表面结构的吸收峰随着R增加产生红移现象. 研究表明当太赫兹波入射角从0°变化到70°时, 该复合超表面结构的太赫兹吸收率均大于90%, 具有完美的广角吸收性能. 如图12所示, 当入射角大于30°时, 在更高频处产生了另外一个吸收峰, 并且随着入射角度继续增加, 该谐振频率也发生轻微红移, 这主要由超表面结构产生高阶模式共振所致.
图 11 不同结构参数对线极化吸收影响 (a) w1; (b) w2; (c) R
Figure 11. Influence of different structural parameters on linear polarization absorption: (a) w1; (b) w2; (c) R.
图 12 线极化太赫兹波入射条件下, 不同入射角对复合超表面结构吸收性能的影响
Figure 12. Different incident angles vs. absorption performance of the designed metasurface composite structure under the linearly polarized terahertz wave incidence.
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本文设计了一种VO2嵌入式复合超表面结构, 可以实现对多个频率点的线极化和圆极化入射波完美吸收. 当VO2绝缘态时, 该超表面能够在1.30 THz处实现对入射LCP太赫兹波的吸收, 同时对入射的RCP太赫兹波产生反射. 当VO2为金属态时, 线极化波入射到超表面, 在频率1.95 THz处实现太赫兹波的完美吸收. 该结构对TE极化和LCP太赫兹波均具有良好的广角吸收性能. 该复合超表面结构能实现不同频率、不同偏振态的太赫兹波产生良好吸收效应, 所以该复合超表面结构的设计构思可用于其他超表面太赫兹器件设计, 而且由于对不同偏振信号的响应特征不同, 可以用于太赫兹成像与传感系统.
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利用VO2嵌入超表面设计了一种实现不同频率, 且线极化和圆极化两种模式入射下均产生高效率吸收的太赫兹超表面. 当VO2为绝缘态时, 设计的超表面对圆极化波的旋向产生选择性吸收, 在1.30 THz处对左旋圆极化波产生的吸收率大于95%, 对右旋圆极化波不吸收, 圆二色性为0.85. 当VO2为金属态时, 在1.95 THz处, 该超表面对TE线极化入射波吸收率达到98.5%. 结果表明, 在线极化和圆极化波入射下, 所设计的超表面结构具有良好的广角吸收性能. 由于它具有形态简单、易于加工等特点, 在太赫兹波传感、成像和通信领域具有广阔的应用前景.In recent years, the development of ultrafast laser technology has provided a stable and reliable terahertz source for generating terahertz wave pulses, and the great research progress of terahertz wave has been made. As a new type of two-dimensional artificial metamaterial, metasurface can effectively control the transmission, reflection and polarization of electromagnetic waves, which has attracted the extensive attention. Most of the reported terahertz absorbers so far are based on metasurfaces with linear polarization incidence, and few studies have been conducted on terahertz metasurfaces that can produce efficient absorption at both linear and circular polarization incidence, which limits the practical application areas. Therefore, it is necessary to explore an efficient absorber which can realize both linear polarization and circular polarization. We propose a vanadium dioxide composite metasurface structure. The vanadium dioxide is a typical temperature-controlled phase change material, and its conductivity will undergo a huge mutation in the phase change process. When the temperature is lower than the critical temperature (68 ℃), the vanadium dioxide has high resistivity and good insulation performance. When the temperature is higher than the critical temperature, the resistance changes from high resistance state to low resistance state, showing metal characteristics. By changing the external temperature, the phase of vanadium dioxide is changed, the free switching frequency is achieved and both the linear polarization and circular polarization incident efficient absorption are realized. When the vanadium dioxide is insulated, its conductivity is 0 S/m, the metasurface can absorb left-handed circularly polarized wave at 1.30 THz and reflect the incident right-handed circularly polarized wave, and the circular dichroism is 0.85. When the vanadium dioxide is metallic, its conductivity is 2×105 S/m and it possesses linearly polarized incident metasurface, the absorption rate of TE linearly polarized incident wave by metasurface reaches 98.5% at 1.95 THz, and the perfect absorption of terahertz wave is realized. The structure has good wide-angle absorption performance for both TE polarization wave and left-handed circularly polarized wave. This composite metasurface structure can achieve the good absorption effect of terahertz waves with different frequencies and different polarization states. Therefore, the design concept of the composite metasurface structure can be used for designing other metasurface terahertz devices, and also for implementing the terahertz imaging and sensing systems due to different response characteristics to different polarization signals.
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Keywords:
- terahertz composite metasurface /
- linearly polarized /
- circularly polarized /
- circular dichroism
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图 1 所设计的工作频率可切换, 对线极化和圆极化入射波均产生完美吸收的太赫兹吸收器结构示意图 (a) 三维结构图; (b) 单元俯视图
Fig. 1. Schematic diagram of the designed terahertz absorber with switchable operating frequency and perfect absorption for both linearly polarized and circularly polarized waves incidence: (a) 3D structure diagram; (b) top view of the unit.
图 2 LCP波和RCP波入射下所设计超表面结构的电磁响应曲线 (a)反射系数; (b)吸收率及圆二色性
Fig. 2. Electromagnetic response curves of the designed metasurface structures under the incident of LCP and RCP waves: (a) Reflection coefficient; (b) absorption and circular dichroism.
图 3 LCP和RCP太赫兹波入射下的电场分布图与电流分布图 (a) RCP入射下的电场分布; (b) LCP入射下的电场分布; (c) RCP入射下的电流分布; (d) LCP入射下的电流分布
Fig. 3. Electric field distribution diagram and current distribution diagram under the LCP and RCP waves incidence: (a) Electric field distribution under RCP incidence; (b) electric field distribution under LCP incidence; (c) current distribution under RCP incidence; (d) current distribution under LCP incidence.
图 4 不同结构参数对所设计超表面的CD影响情况 (a) 线宽w1; (b) 线宽w2; (c) 间隙θ
Fig. 4. Influence of different structural parameters on the CD of the designed metasurface: (a) Line width w1; (b) line width w2; (c) angle θ
图 5 入射角对所设计超表面的吸收特性影响 (a) LCP; (b) CD
Fig. 5. Incident angle vs. absorption properties of the designed metasurface: (a) LCP; (b) CD.
图 6 TE波和TM波入射下所设计结构的电磁响应曲线 (a) 反射系数; (b) 吸收率
Fig. 6. Electromagnetic response curves of the designed structures under the incident of TE and TM waves: (a) Reflection coefficient; (b) absorption.
图 7 LCP和RCP太赫兹波入射到所设计超表面结构产生的电磁响应曲线 (a) 反射系数; (b) 吸收率及圆二色性
Fig. 7. Electromagnetic response curves of the designed structures under LCP and RCP waves incidence: (a) Reflection coefficient; (b) absorption and circular dichroism.
图 8 TE和TM极化太赫兹波入射到复合超表面结构产生的电磁响应曲线 (a) 反射谱; (b) 吸收谱
Fig. 8. Electromagnetic response curves of TE and TM polarized terahertz wave is incident on the designed composite metasurface structure: (a) Reflection coefficient; (b) absorption coefficient.
图 9 TE波入射到复合超表面结构产生的等效阻抗实部与虚部
Fig. 9. Real and imaginary parts of the equivalent impedance of the designed composite metasurface structure under the TE wave incidence.
图 10 TE波入射下, 复合超表面结构电场分布
Fig. 10. Electric field distribution of the designed composite metasurface structure under TE wave incidence.
图 11 不同结构参数对线极化吸收影响 (a) w1; (b) w2; (c) R
Fig. 11. Influence of different structural parameters on linear polarization absorption: (a) w1; (b) w2; (c) R.
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[1] Chen L, Liao D G, Guo X G, Zhao J Y, Zhu Y M, Zhuang S L 2019 Front Inform. Technol. Electron. Eng. 20 591
Google Scholar
[2] Xu B L, Zhong R B, Liang Z K, et al. 2022 Front Mater 9 881229
Google Scholar
[3] Zheng Z P, Luo Y, Yang H, et al. 2022 Phys. Chem. Chem. Phys. 24 8846
Google Scholar
[4] Zhang Y G, Qiu F, Liang L J, Yao H Y, Yan X, Liu W J, Huang C C, Yao J Q 2022 Opt. Express 30 24703
Google Scholar
[5] Tang B, Ren Y 2022 Phys. Chem. Chem. Phys. 24 8408
Google Scholar
[6] Luo H, Wang X, Qian H 2021 J. Opt. Soc. Am. B 38 2638
Google Scholar
[7] Aghili S, Amini A, Dizaj L S, Dolgaleva K 2022 Opt. Commun. 508 127805
Google Scholar
[8] Zhu L, Zhao X, Miao F J, Ghosh B K, Dong L, Tao B R, Meng F Y, Li W N 2019 Opt. Express 27 12163
Google Scholar
[9] Zhang Y D, Liu H Q, Xu R G, Qin Z J, Teng C X, Deng S J, Chen M, Cheng Y, Deng H C, Yang H Y, Qu S L, Yuan L B 2021 Opt. Express 29 21020
Google Scholar
[10] Wang X Y, Ma C, Xiao L H, et al. 2022 Appl. Opt. 61 1646
Google Scholar
[11] Li R, Pan M, Yi Z, Yu J X, Shi P C, Luo H, Wu P H, Yang H, Wang S F, Gao G C 2022 Opt. Laser Technol. 153 108284
Google Scholar
[12] Chen X Y, Tian Z, Lu Y C, Xu Y H, Zhang X Q, Ouyang C M, Gu J Q, Han J G, Zhang W L 2020 Adv. Optical Mater. 8 1900660
Google Scholar
[13] Hu N, Wu F L, Bian L A, Liu H Q, Liu P G 2018 Opt. Mater. Express 8 3899
Google Scholar
[14] 杨鹏 韩天成 2018 物理学报 67 107801
Google Scholar
Yang P, Han T C 2018 Acta Phys. Sin. 67 107801
Google Scholar
[15] Yan D X, Li J S 2019 Laser Phys. 29 046203
Google Scholar
[16] Divdel H, Taghipour-Farshi H, Saghai H R, Jahani M A T G 2020 Opt. Eng. 59 127108
Google Scholar
[17] Zhao Y, Zeng L, Zhang X L, Ye H N, Zhang H F 2021 J. Opt. 23 085102
Google Scholar
[18] Liang S, Zhu Z B, Jiang L Y 2022 Eng. Res. Express 4 035006
Google Scholar
[19] Li Z W, Li J S 2021 Appl. Opt. 60 2450
Google Scholar
[20] Mutlu M, Akosman A E, Serebryannikov A E, Ozbay E 2012 Phys. Rev. Lett. 108 213905
Google Scholar
[21] Wang T L, Zhang Y P, Zhang H Y, Cao M Y 2020 Opt. Mater. Express 10 369
Google Scholar
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